Very widely differing embodiments of flat detectors are used as X-ray detectors, inter alia in medicine. The purpose of the different sizes and formats, in particular the rectangular shape, is, for example, optimized patient access and matching to the respective examination area (for example in cardiology, angiography and radiography).
In many X-ray appliances, it is possible to rotate the detector, as is the case by way of example on each C arc, in order to use the detector to optimally display the image area to be examined and/or the image format in conjunction with the respective angulation. For example, detectors with a rectangular usable image format, which are used for specific multifunctional applications, are frequently rotated through 90° during the examination.
Non-square detectors, in particular, are subject to the problem that the correction images that are used from the calibration were acquired with the detector in only one fixed position with respect to the X-ray tube. This results in reduced image quality or image artifacts, caused by the different position of the detector relative to the tube (including heeling effect, shadowing, different pixel sensitivity in the detector edge areas).
Finally, the above effects such as shadowing in edge and corner regions of the detector can lead to increased spurious pixel defect identification in those areas.